1. Field of the Invention
The present invention relates to a remote-controlled rearview mirror assembly such as automobile door mirror assembly, of which the mirror is supported freely tiltably relative to the housing thereof, and more particularly, to an improved and novel electrically remote-controlled type mirror assembly, of which the mirror can be quickly and simply tilted vertically beyond the adjustable range of the mirror angle for ordinary driving of a car in order to view the car rear wheel and its vicinity.
2. Prior Art Statement
An electrical remote-control type automobile mirror assembly is disclosed in, for example, the U.S. Pat. No. 4,555,166, of which the mirror is supported tiltably relative to the housing thereof and can be turned vertically and horizontally by means of remote-controlled motors.
FIGS. 1 and 2 show together an example of the well-known mirror assembly of this type.
FIG. 1 is a front view showing the drive unit from which the mirror body is removed, the casing 1 of the drive unit being partially cut off. FIG. 2 is a sectional view taken along the line II--II, showing the drive unit, shown in FIG. 1, to which the mirror body is mounted.
Two axes X--X' and Y--Y' perpendicular to each other are set as shown in FIG. 1. There is provided at the intersection 0 of these axes a ball-and-socket joint 2 by which the mirror body 3 is tiltably supported as shown in FIG. 2. The reference numeral 4 indicates a mirror proper.
As shown in FIG. 1, plungers 5 are provided on the axes X--X' and Y--Y', respectively. The plunger 5 has provided at the end thereof a ball-and-socket joint 6 coupled to the mirror body 3, as shown in FIG. 2. The plunger 5 has formed axially therein a recess 7 in which a projection 8 provided on the drive casing 1 is engaged against axial pivoting of the plunger 5 relative to the drive housing, and it has fitted thereon a gear 9 at the last step of speed reduction. The gears 9 are rotated by motors 10, respectively, each by means of a speed reduction gear train 11.
As described above, the plunger 5 is blocked against axial pivoting and has formed on the outer circumference thereof a male thread which is in mesh with the gear 9. Thus, as the gear 9 is rotated, the plunger 5 is axially driven to tilt the mirror body 3.
The adjustable range of the angular position of the mirror 4 tilted by the above-mentioned drive unit (see FIGS. 1 and 2) is so set as to cover the necessary viewing range for an ordinary driving of the car on the road. Also, the tilt speed of the mirror body 3 is limited to such an extent as to be adjustable with an accuracy required in practice. This is because if the mirror body is tilted too quickly, it is rather difficult to adjust the tilt angle as desired.
However, in any special driving of the car, for example, when moving the car backward in the vicinity of a road edge or in the direction of its width, it is desired in some cases to have a vision of the rear wheel and its vicinity, of which the image is viewed as reflected by the door mirror (this vision will be referred to as "reflected image" hereinafter).
FIG. 3 is a schematic explanatory drawing showing the relation between the mirror angle and field of view.
The point "Eye" in FIG. 3 indicates the position of the driver's eyes. To view a car behind or the like in the ordinary driving of a car, the door mirror posture (theoretically a door mirror angle relative to the road surface, or practically a door mirror angle relative to the car body--this angle will be referred to as "mirror angle" hereinafter) is so adjusted as to view the reflected image within the angular range .theta. shown in FIG. 3.
When moving the car backward in the vicinity of a road edge, the reflected image within the angle .phi. in FIG. 3 can desirably be viewed by tilting down the mirror body. For this desirable condition, it is required that the rear wheel should be within the angular range .phi. and that the road surface over the distance D necessary for knowing the position of the car behind should also be within this angular range .phi..
For the driver to view the reflected image of the rear wheel and its vicinity, the door mirror should be tilted down through a predetermined angle from the mirror angle set for rear viewing during ordinary driving of the car. Varying from one car model to another, the predetermined angle ranges from 5.degree. to 7.degree.. Concerning a certain car model, the predetermined angle is generally constant irrespective of the driver's sitting height.
Indeed in the conventional remote-controllable door mirrors, the range of the mirror tilt by the drive unit can be increased for the driver to view the rear wheel and its vicinity; such door mirrors are disadvantageous in the following:
(a) If the normal adjustable range of the mirror angle is increased with the mirror tilt speed not changed, the time taken for the mirror operation is longer;
(b) If the mirror tilt speed is increased correspondingly to the increase of the adjustable range of the mirror angle, the mirror angle cannot be adjusted accurately for rear viewing during ordinary car driving; and
(c) Further in any of the above two cases, once the mirror posture is changed from a position in which the mirror angle is so set that the reflected image within the angular range .theta. shown in FIG. 3 can be viewed (which position will be referred to as "rear-viewing position for ordinary car driving" hereinafter) to a state in which the mirror angle is so set that the reflected image within the angular range .phi. shown in FIG. 3 can be viewed (which position will be referred to as "rear-viewing position for rear-wheel checking" hereinafter), the mirror angle must be readjusted to restore the rear-viewing position for ordinary car driving because the initial angular position has been lost.